Containers for beverages such as milk, cream, other dairy products, juices, and the like are conventionally constructed from thermoplastic coated paperboard. One type of these containers includes a top end closure with a folded gable roof having a vertically projecting seal at the roof ridge for sealing the container and providing a pouring spout when the contents of the container are to be dispensed. Stacking of such containers requires the use of separating trays intermediate different layers due to the vertically projecting seals of their top end closures. Also, storage space is lost in stacking these containers due to the empty space resulting from the configuration of the top end closure. Such containers are shown by U.S. Pat. Nos. 3,116,002 and 3,120,335. Another type of the containers include flat top end closures that are folded and have a flat seal projecting from a centerline of the closure with an outer end that is releasably secured to the rest of the closure generally adjacent one of its sides. Various releasable securements are provided for releasing the flat seals to permit them to be opened and to thereby provide a pouring spout for dispensing the beverages. U.S. Pat. Nos. 3,869,078 and 3,892,347 disclose such flat top end closures. A further type of container is disclosed by U.S. Published Patent application No. B461,257, published Jan. 13, 1976, now U.S. Pat. No. 4,078,715, issued Mar. 14, 1978, and includes a top end closure with an inclined seal that includes a harder score line on one side of the seal for facilitating folding of the seal from a vertical position to the inclined position.
U.S. Pat. Nos. 4,012,997 and 4,093,115 disclose a container folding method and the container made by the method wherein certain roof panels of the top end closure are provided with double score lines extending alongside each other. Folding of a top seal of the end closure from a vertical position to a flat position requires the application of a downward force along the lower double score line on one side of the top seal and the application of another force to bend the top seal downwardly. Each additional application of force for folding the top end closure requires an additional folding tool on the folding mechanism and is thus accompanied by additional expense.
Coated paperboard blanks for constructing each type of container described above are made on converting machines like those disclosed by U.S. Pat. Nos. 2,682,208 and 3,731,600. After construction of the blanks to form the containers, application of heat or high frequency vibration applied by clamping pressure to interengaged portions of the blanks provides sealing of the containers.